MechWarrior is a role-playing game (RPG) based on and set in the BattleTech universe. The player usually takes on the role of a MechWarrior, but other career paths are available (increasingly so in later iterations of the game). The RPG was intended to expand a player's experience beyond just the board game aspect. It allows them to create a character who could then earn experience both in 'Mech combat and in role-playing scenarios. The character's experience could then be used to improve their board game skills (particularly in Piloting and Gunnery) and other RPG skills.

Four versions of the RPG have been published, all with different rulesets:

The third edition includes a character creation system that is similar to FASA's original Star Trek role-playing game. It fixed many of the issues introduced by the second edition rules.When Catalyst Game Labs took over the BattleTech license and product line from FanPro, BattleTech was renamed to Classic BattleTech to differentiate it from the new MechWarrior: Dark Age game that WizKids launched at that time. Because the term "MechWarrior" was used for the new game, the existant third edition of the RPG was re-published by CGL with a new cover and renamed to Classic BattleTech RPG, without changing its content except for errata.

The fourth edition (A Time of War) was rewritten from the ground up, to adress perceived balancing issues and the very random character creation of the third edition. A Time of War is the first one not published under the "MechWarrior" moniker. "A Time of War" had previously been the title of the introductory fiction in the third edition.